function Contacts() {
  return <div className="Contacts" />;
}

function Chat() {
  return <div className="Chat" />;
}

function SplitPane(props) {
  return (
    <div className="SplitPane">
      <div className="SplitPane-left">
        {props.left}
      </div>
      <div className="SplitPane-right">
        {props.right}
      </div>
    </div>
  );
}

function App() {
  return ( < SplitPane left = {
      <Contacts />
    }
    right = {
      <Chat />
    }
    />
  );
}

ReactDOM.render(
  <App />,
  document.getElementById('root')
);